Circular RNA P4HB promotes glycolysis and tumor progression by binding with PKM2 in lung adenocarcinoma.

BACKGROUND: Emerging evidence indicates that circular RNAs (circRNAs) play vital roles in tumor progression, including lung adenocarcinomas (LUAD). However, the mechanisms by which circRNAs promote the progression of LUAD still require further investigation. METHODS: Quantitative real-time PCR was performed to detect the expression of circP4HB in LUAD tissues and cells. Then, Kaplan-Meier analysis was used to determine the prognostic value of circP4HB expression. We employed RNA pull-down, RNA immunoprecipitation, mass spectrometry, cells fraction, glucose consumption, lactate production, pyruvate kinase M2 (PKM2) activity, and macrophage polarization assays to uncover the underlying mechanisms of circP4HB in LUAD. RESULTS: We found that circP4HB is upregulated in LUAD tissues and correlated with advanced TNM stages and lymph node metastasis. LUAD patients with high circP4HB expression had poor prognoses. Functionally, circP4HB promoted LUAD progression in vivo and in vitro. Upregulated circP4HB increased glucose consumption, lactate production and accelerated aerobic glycolysis in LUAD cells. Mechanically, circP4HB mainly accumulated in the cytoplasm of LUAD cells and bound with PKM2 and subsequently upregulating PKM2 enzymatic activity by increasing its tetramer formation. Additionally, circP4HB promoted M2 macrophage phenotype shift via targeting PKM2. Finally, rescue assays further confirmed that circP4HB could promote LUAD cell progression through its interaction with PKM2. CONCLUSION: These results demonstrate that circP4HB could promote LUAD progression, indicating circP4HB might be a potential therapeutic target of LUAD.

Circular RNA, circular RARS, promotes aerobic glycolysis of non-small-cell lung cancer by binding with LDHA.

PURPOSE: Accumulating evidence has highlighted the critical roles of circular RNAs (circRNAs) in non-small-cell lung cancer (NSCLC). This study aims to unveil the roles of circRARS (circular RARS) (hsa_circ_0001551) in NSCLC. METHODS: Quantitative real-time PCR was used to determine the expression of circRARS in NSCLC tissues and cells. Kaplan-Meier analysis was used to determine the prognostic value of circRARS expression. CCK8, transwell, and wound healing assays were used to assess the proliferation, invasion, and migration abilities of NSCLC cells. RNA pull-down, cell fraction, glucose consumption, lactate production, and lactate dehydrogenase activity assays were conducted to explore the potential mechanisms of circRARS in NSCLC. RESULTS: circRARS is upregulated in NSCLC tissues and positively correlated with smoking status, lymph node metastasis, and higher tumor stages. NSCLC patients with high expression of circRARS have poor overall survival. Functional assays demonstrated that circRARS accelerated the proliferation, invasion, and migration of NSCLC cells in vitro. The cell fraction suggested that circRARS mainly accumulated in cytoplasm and the RNA pull-down assay showed lactate dehydrogenase (LDHA) could bind with circRARS. Furthermore, circRARS positively regulates LDHA activity and LDHA expression at the transcription level. Moreover, downregulated circRARS decreases glucose consumption and lactate production and compromises aerobic glycolysis in NSCLC cells. Finally, rescue assays showed circRARS could promote NSCLC cell proliferation by regulating LDHA activity. CONCLUSION: This study shows that circRARS can promote glycolysis and tumor progression in NSCLC by regulating LDHA.

Integrative Analyses of Circulating mRNA and lncRNA Expression Profile in Plasma of Lung Cancer Patients.

Circulating-free RNAs (cfRNAs) have been regarded as potential biomarkers for "liquid biopsy" in cancers. However, the circulating messenger RNA (mRNA) and long noncoding RNA (lncRNA) profiles of lung cancer have not been fully characterized. In this study, we profiled circulating mRNA and lncRNA profiles of 16 lung cancer patients and 4 patients with benign pulmonary nodules. Compared with benign pulmonary nodules, 806 mRNAs and 1,762 lncRNAs were differentially expressed in plasma of lung adenocarcinoma patients. For lung squamous cell carcinomas, 256 mRNAs and 946 lncRNAs were differentially expressed. A total of 231 mRNAs and 298 lncRNAs were differentially expressed in small cell lung cancer. Eleven mRNAs, 51 lncRNAs, and 207 canonical pathways were differentially expressed in lung cancer in total. Forty-five blood samples were collected to verify our findings via performing qPCR. There are plenty of meaningful mRNAs and lncRNAs that were found. MYC, a transcription regulator associated with the stemness of cancer cells, is overexpressed in lung adenocarcinoma. Transforming growth factor beta (TGFB1), which plays pleiotropic roles in cancer progression, was found to be upregulated in lung squamous carcinoma. MALAT1, a well-known oncogenic lncRNA, was also found to be upregulated in lung squamous carcinoma. Thus, this study provided a systematic resource of mRNA and lncRNA expression profiles in lung cancer plasma.

Comprehensive Analysis of the Immune and Prognostic Implication of COL6A6 in Lung Adenocarcinoma.

Collagen type VI alpha 6 chain (COL6A6), a novel collagen, has been considered as a tumor suppressor and therapeutic target in several tumors. However, the functional role of COL6A6 in immune cell infiltration and prognostic value in lung adenocarcinoma (LUAD) remains unknown. Here, we evaluated COL6A6 expression and its impact on survival among LUAD patients from The Cancer Genome Atlas (TCGA) and several other databases. COL6A6 was downregulated in LUAD tissues compared to normal tissues at both mRNA and protein levels. COL6A6 expression was negatively associated with pathological stage, tumor stage, and lymph node metastasis. High COL6A6 expression was a favorable prognostic factor in LUAD. Next, we explored the associations between COL6A6 expression and immune cell infiltration. COL6A6 expression was positively associated with the infiltration of B cells, T cells, neutrophils and dendritic cells. Additionally, the immune cell infiltration levels were associated with COL6A6 gene copy number in LUAD. Consistently, gene set enrichment analysis showed that various immune pathways were enriched in the LUAD samples with high COL6A6 expression, including pathways related to T cell activation and T cell receptor signaling. The impacts of COL6A6 on immune activity were further assessed by enrichment analysis of 50 COL6A6-associated immunomodulators. Thereafter, using Cox regression, we identified a seven-gene risk prediction signature based on the COL6A6-associated immunomodulators. The resulting risk score was an independent prognostic predictor in LUAD. Receiver operating characteristic curve analysis confirmed that the seven-gene signature had good prognostic accuracy in the TCGA-LUAD cohort and a Gene Expression Omnibus dataset. Finally, we constructed a clinical nomogram to predict long-term survival probabilities, and calibration curves verified its accuracy. Our findings highlight that COL6A6 is involved in tumor immunity, suggesting COL6A6 may be a potential immunotherapeutic target in LUAD. The proposed seven-gene signature is a promising prognostic biomarker in LUAD.

Decoding the multicellular ecosystem of lung adenocarcinoma manifested as pulmonary subsolid nodules by single-cell RNA sequencing.

Lung adenocarcinomas (LUAD) that radiologically display as subsolid nodules (SSNs) exhibit more indolent biological behavior than solid LUAD. The transcriptomic features and tumor microenvironment (TME) of SSN remain poorly understood. Here, we performed single-cell RNA sequencing analyses of 16 SSN samples, 6 adjacent normal lung tissues (nLung), and 9 primary LUAD with lymph node metastasis (mLUAD). Approximately 0.6 billion unique transcripts were obtained from 118,293 cells. We found that cytotoxic natural killer/T cells were dominant in the TME of SSN, and malignant cells in SSN undergo a strong metabolic reprogram and immune stress. In SSN, the subtype composition of endothelial cells was similar to that in mLUAD, while the subtype distribution of fibroblasts was more like that in nLung. Our study provides single-cell transcriptomic profiling of SSN and their TME. This resource provides deeper insight into the indolent nature of SSN and will be helpful in advancing lung cancer immunotherapy.

A novel circular RNA, circXPO1, promotes lung adenocarcinoma progression by interacting with IGF2BP1.

Studies have demonstrated that noncoding RNAs play important roles in various types of cancer; however, noncoding RNAs derived from regions of genomic alterations have rarely been explored, especially for circular RNAs (circRNA). Previously, we found several circRNAs were upregulated in lung adenocarcinoma (LUAD) tumor tissues by RNA sequencing. Here, we characterized a novel circRNA, circXPO1, in LUAD, which is derived from a well-established cancer therapeutic target, XPO1. circXPO1, is formed by back-splicing of exon 3 and exon 4 of XPO1 gene. circXPO1 was highly expressed in LUAD tissues compared with paired adjacent non-tumor tissues, and high circXPO1 expression correlated with worse overall survival. circXPO1 expression was positively correlated with the XPO1 gene copy number. Mechanically, circXPO1 could bind with IGF2BP1 and enhance CTNNB1 mRNA stability, and subsequently promote LUAD progression. In a LUAD patient-derived xenograft model, intratumoural injection of cholesterol-conjugated siRNA specifically targeting circXPO1 efficiently suppressed tumor growth. To summary, these results suggest that circXPO1 is critical for LUAD progression and may serve as a biomarker for poor prognosis and a therapeutic target. On the other hand, the functional roles of noncoding transcripts derived from coding genes should be re-evaluated.

Highly Sensitive Droplet Digital PCR Method for Detection of de novo EGFR T790M Mutation in Patients with Non-Small Cell Lung Cancer.

OBJECTIVE: The aim of this study was to investigate the allelic relation between de novo T790M and concomitant sensitizing EGFR mutations in EGFR-TKIs naïve NSCLCs and to explore whether the formalin-fixed and paraffin-embedded (FFPE) materials affect the detection of de novo EGFR T790M mutation. METHODS: Specimens of 300 consecutive EGFR-TKI naïve NSCLCs who received surgical resection between January 2016 and June 2018 were retrospectively investigated. All the snap-frozen tumor tissues from 300 NSCLCs were screened by droplet digital PCR (ddPCR) for the detection of de novo T790M mutation. The allelic relation between de novo T790M mutation and concomitant sensitizing EGFR mutations was also investigated. Furthermore, we assessed de novo T790M mutation in paired FFPE specimens of 50 patients which included tumor tissues and paired normal lung tissues of the pretreatment NSCLCs to investigate whether FFPE materials affect the detection of de novo T790M mutation. RESULTS: The de novo T790M mutation was observed in four patients which included one patient of single de novo T790M mutation and three patients of de novo T790M mutation coexisting with L858R mutation. The incidence of de novo T790M in pretreatment NSCLCs who harboring EGFR mutations was 2.9% (4/139). All the de novo T790M mutations were detected in cis with the concomitant L858R mutations for the three NSCLCs. Our ddPCR method demonstrated that the frequency of de novo T790M mutation was ranging from 0.1% to 0.5% among 90% (45/50) of the FFPE tumor samples and 92% (46/50) of the paired FFPE adjacent normal lung samples. The frequency of de novo T790M mutation in the paired snap-frozen samples was all below 0.1%. CONCLUSION: Our study demonstrated that most de novo T790M mutations were detected in cis with concomitant sensitizing mutations for pretreatment NSCLCs. Analytical cut-off of ddPCR assay for FFPE specimens should be validated carefully considering the possibility of FFPE-derived artificial gene mutations.

Characterization of gene expression profiles of esophageal cancer patients with different nonsynonymous tumor mutation burden.

BACKGROUND: Nonsynonymous tumor mutation burden (NSTMB) could affect the prognosis of esophageal cancer (EC) patients, but differentially expressed genes between EC patients with different NSTMB have not been explored. Our study aimed to compare differentially expressed genes between EC patients with different NSTMB (high vs. low). METHODS: RNA-seq data for EC patients were downloaded from The Cancer Genome Atlas (TCGA). The edgeR package was used to identify differentially expressed genes between patients with different NSTMB. Cell type identification by estimating relative subsets of known RNA transcripts (CIBERSORT) software was employed to underscore immune cell differences between patients with different NSTMB. RESULTS: In total, we discovered 2215 differentially expressed genes between patients with different NSTMB, among which 842 genes were upregulated and 1373 downregulated in patients with high NSTMB. The differentially expressed genes were enriched in pathways such as heme binding and structural molecule activity. We built a logistic model that may be used to predict patients' NSTMB. We found that tumors with high NSTMB had a significantly higher percentage of resting natural killer (NK) cells than those with low NSTMB (P = 0.028). The percentages of regulatory T (Treg) and CD8+ T cells were also higher in those with high NSTMB, although it was not statistically significant (P = 0.064 for Treg cells and P = 0.12 for CD8+ T cells). CONCLUSIONS: NSTMB may cause changes in gene expression and immune cell infiltration in EC patients, and affect the overall survival of EC patients. KEY POINTS: Significant findings of the study This study found differentially expressed genes and differences in infiltration of immune cells between esophageal cancer (EC) with different NSTMB. What this study adds This study highlights differences between EC patients with different NSTMB.

Lymph node dissection and survival in patients with early stage nonsmall cell lung cancer: A 10-year cohort study.

It is still debatable whether complete mediastinal lymph node dissection (MLND) is associated with better survival than mediastinal lymph node sampling (MLNS) in surgical treatment of nonsmall cell lung cancer (NSCLC). We aimed to assess the impact of lymph node dissection on long-term survival among stage I NSCLC patients.In this cohort study, 317 stage I NSCLC Chinese patients in Shanghai Chest Hospital were followed up for at least 10 years to evaluate the impact of different lymph node dissection modes on their survival. Among them, 161 patients were in the MLND group and 156 in the MLNS group. Overall survival and median survival times were calculated for the 2 groups. The association between lymph node dissection and the survival of NSCLC patients was assessed using Cox proportional-hazard models.Patients in the MLND group presented better survival (median survival time = 154.67 months) than those in the MLNS group (median survival time = 124.67 months). The MLNS had higher mortality than the MLND group, with the crude hazard ratio of the MLNS group relative to the MLND group as 1.32 (95% confidence interval [CI] 0.97, 1.78). After adjusting for age and sex, the association between lymph node dissection and mortality (hazard ratio 1.36, 95% CI 1.00, 1.84) was statistically significant (P = .047). Further adjusting for baseline clinical characteristics, the association (hazard ratio 1.40, 95% CI 1.02, 1.92) remained statistically significant (P = .036). The association between lymph node dissection mode and mortality was strong among patients with tumor size between 2.0 and 3.0 cm (hazard ratio 2.79, 95% CI 1.45, 5.37).We found that the MLND was associated with better survival for patients with early-stage NSCLC, compared with the MLNS. The effects of MLND on survival may depend on tumor size. Our findings have important implications in the treatment of early-stage NSCLC. Further prospective studies with a large sample size are needed to confirm our findings.

[Analysis on the Prognostic and Survival Factors of Synchronous Multiple Primary Lung Cancer].

BACKGROUND: Synchronous multiple primary lung cancer (sMPLC) is a sparse disease in the past, but there has been a gradual increase in the morbidity of sMPLC recently. However, studies on large sample have never been undertaken. The purpose of this study is to investigate the diagnosis, treatment and prognosis of sMPLC through analyzing the clinical data, and provide supports for the management of sMPLC. METHODS: According to Martini-Melamed criteria, 357 patients were diagnosed sMPLC. The pathological staging is on the basis of the 8th edition tumor-node-metastasis (TNM) staging from International Association for the Study of Lung Cancer (IASLC). RESULTS: There were 269 patients with double primary lung cancer, 65 patients with triple primary lung cancer and 23 patients with four or more primary lung cancer. Lesions (68.55%, 571/833) were frequently in upper lobe, especially the right upper lobe. Adenocarcinoma (95.56%, 796/833) was the mainly pathological type, followed by squamous cell carcinoma (2.40%, 20/833). The acinar predominant subtype was the main part (70.81%, 313/442) of the all adenocarcinoma specimens. Most of the lesions (68.35%, 244/357) were stage Ib or low. Among the initial lesion and the following lesions ,patients who had the same pathological type (92.72%, 331/357) were more than the different (7.28%, 26/357), of which adenocarcinoma-adenocarcinoma occupied the major proportion (99.40%, 329/331). The 3-year overall survival (OS) and 5-year overall survival were respective 91.93% and 84.37%. Multivariate analysis found that smoking history (P=0.012), the diameter of the maximum lesion (P=0.027), lymph node metastasis (P=0.015) and pleural invasion (P<0.001) were the independent risk factors for prognosis. CONCLUSIONS: Tumours in patients with sMPLC are more frequently in the right upper lobe. Adenocarcinoma was the mainly pathological type. Smoking history, the diameter of the maximum lesion, lymph node metastasis and pleural invasion were the independent risk factors for prognosis. Early diagnosis and active operation can obtain better prognosis.

[Research Progress in Diagnosis and Management Strategies 
of Multiple Primary Lung Cancer].

Although the morbidity of multiple primary lung cancer (MPLC) has been increasing year by year, it is still controversial about pathogenesis, differential diagnosis and management strategies of MPLC. This review provides a snapshot of the main progress of pathogenesis, differential diagnosis and management strategies of MPLC.